PB2420: DEVELOPMENT AND VALIDATION OF THE PRACT MODEL FOR ALLOGENEIC HAEMATOPOIETIC STEM CELL TRANSPLANTATION IN PATIENTS ABOVE 60 YEARS OLD WITH HAEMATOLOGICAL MALIGNANCIES IN A REAL-WORLD STUDY
Authors: Jing Liu, Qiu-Sha Huang, Xiao-Hui Zhang
Journal: HemaSphere (2023)

Topic: 22. Stem cell transplantation - Clinical Background: Allogeneic haematopoietic stem cell transplantation (allo-HSCT) offers the best potential to cure haematological malignancies. There is also an increasing need for allo-HSCT. However, transplantation-related mortality remains an issue, particularly in older patients. Aims: We aimed to assess transplant outcomes, especially transplantation-related mortality (TRM), and the feasibility of using allo-HSCT in older patients. Methods: We collected data from a total of 185 patients above 60 years old with acute haematological malignancies who received allo-HSCT from 19 Mar 2011 to 28 Aug 2022 in our hospital and conducted a real-world study to develop and validate a prognostic model for older patients. The derivation cohort included 108 patients receiving allo-HSCT from April 2011 to October 2020, and the validation cohort included 88 patients receiving allo-HSCT from November 2020 to August 2022. We assessed 21 clinical parameters as candidate risk factors and used multivariable Cox regression to develop our prognostic model. Results: From 19 Mar 2011 to 28 Aug 2022, a total of 185 patients above 60 years of age with acute haematological malignancies who received allo-HSCT were included in this study. The last follow-up date was 24 Nov 2022, and the median follow-up was 478 (22-2854) days. The cumulative incidence of TRM on day 100, 1 year, and 2 years was 5.9% (95% CI, 5.8%-6.0%), 18.3% (95% CI, 18.1%-18.5%), and 23.3% (95% CI, 23.1%-23.5%), respectively. Lastly, 40 patients died of TRM, among whom 11 patients died within 100 days after HSCT, two due to TMA, two due to aGVHD and TMA simultaneously, and one due to capillary leak syndrome. Through a Cox regression analysis, which was used to determine the risk factors for the cumulative incidence of TRM in older patients who received allo-HSCT, platelet engraftment failure, conditioning regimen, aGVHD III-IV, CMV disease, and thrombotic microangiopathy (TMA) were included in the prognostic model named PRACT. We validated the PRACT model in a temporal validation cohort. The PRACT model had an AUC of 0.875 in the derivation cohort and 0.943 in the validation cohort (Figure 1a-b). Calibration plots demonstrated good consistency between the PRACT-predicted probability and actual observation in both internal validation and external validation (Figure 1c-d). Lastly, we performed a decision curve analysis (DCA) to assess the net benefit of older patients receiving allo-HSCT when using the PRACT scoring model in the clinic in the derived cohort and the validation cohort(Figure 1 e-f). Summary/Conclusion: Allo-HSCT is a feasible option for older patients with haematologic malignancies and should be considered more frequently.Figure 1 ROC curve of the prognostic model for predicting TRM in elderly patients in the derivation cohort (a) and the validation cohort (b). Calibration plot of the prognostic model for predicting TRM in elderly patients in the derivation cohort (c) and the validation cohort (d). Decision curve analysis of the prognostic model for predicting TRM in elderly patients in the derivation cohort (e) and the validation cohort (f). Red line: assumes that no patient has poor prognosis; green line: assumes all patients have poor prognosis. These two lines serve as references. Keywords: Allogeneic hematopoietic stem cell transplant, Prognostic, HSCT, Old